Photovoltaic solar panels can be the cause of irreversible degradation in performance when exposed to light in open circuit over a long period. In particular, when the photovoltaic panels are installed on a site waiting to be connected to an electricity evacuation grid, they are exposed to light and are in open circuit. This phenomenon penalises the profitability of photovoltaic projects whereof the date of attachment to the electricity evacuation grid occurs several months after installation of photovoltaic modules.
One of the solutions known to date is to position on the direct current circuit of photovoltaic panels, resistors of fixed load directly at output of the solar modules. But this solution, the advantage of which is being inexpensive, fails to control the operation point of the photovoltaic panels as a function of solar radiation and therefore does not meet needs. In fact, manufacturers of photovoltaic panels recommend having them supply always at the point of maximum power.
Document US-A-2013/00 63 993 describes an emulator of alternating grid to be attached to the inverter of a photovoltaic generator. This emulator comprises a bank of resistors which can be selectively connected by switchs to the AC side of the photovoltaic inverter of the photovoltaic generator. Also, a source of alternating current is attached to the AC side of the photovoltaic inverter and in parallel with the bank of resistors. This document indicates that in case of rapid variations in power to be dissipated the source of alternating current has a sufficient margin to regulate the equivalent resistance of the bank of resistors to prevent current from reversing to this source. This source of alternating current can be a programmable source according to this document, this source in turn being connected to an electric power grid.
Consequently, the device described by this document has limitations as to the use of a source of alternating current and is complicated to execute.
Document CN-U-2028 18 122 describes an alternating grid emulator, comprising an AC to DC conversion module, an IGBT, a serial-parallel output module, a filtering circuit and a three-phase output circuit.
This device also has the disadvantage of needing a source of alternating current, this source in turn being connected to an electric power grid.
In this way, each of the devices described by both documents US-A-2013/00 63 993 and CN-U-2028 18 122 needs a source of alternating current, whereas the aim is to just be able to simulate on the AC side the presence of a grid of alternating current without making a connection to such a grid of alternating current.